1. Field of the Invention
The present invention relates to electromagnetic actuators and more particularly to solenoid devices of improved design to facilitate maintaining close tolerances between the bobbin and the plunger while avoiding binding or jamming of the plunger during operation.
2. Description of the Prior Art
Electromagnetic actuators convert electrical impulses into mechanical action and perform many functions, especially in modern remote sensing and control applications. Many of these control applications require that the mechanical action produced by the actuators conform to strict requirements and tolerances. In solenoids for producing precise mechanical action, the plunger or armature must fit closely in the well to eliminate any play or "chatter" between it and the sidewalls of the well. In many such solenoids the aramature must also move longitudinally in the well of the solenoid without rotating. It is highly desirable that these operational parameters be attainable in very small solenoid devices which can be produced at low costs and which will operate reliably, e.g., without jamming or binding.
Many prior art solenoids for producing mechanical action conforming to strict requirements and precise tolerances are intricate devices having a multiplicity of close tolerance components. Several of these solenoids have armatures with plates or other components mounted on them to eliminate rotation and "chatter" and to stop the armature at precise predetermined positions. Other solenoids use complicated housing designs, permanent magnets and other close tolerance components made of various materials to provide precise, uniform and reliable performance. Producing such prior art solenoids require accurate and expensive machines and machining techniques, processes, and the use of costly materials. In addition, the complexities of the prior art devices make them susceptible to malfunctions such as binding or jamming and breakdowns particularly in small and, hence, lightweight devices.
The solenoid of the present invention provides a mechanism having a coil or winding bobbin with a central well or opening that contains the solenoid's armature, prevents it from rotating and "chattering", and allows it to provide a precise, uniform and reliable mechanical action. It provides a construction which greatly minimizes the expense of manufacture and assembly. The solenoid of the present invention comprises a small number of components with sufficiently accurate and consistent tolerances to produce the requisite mechanical action and place the armature in proper position and alignment.